Which of the following observations most strongly supports the view that mitochondria contain electron transfer enzymes aggregated into compact associations?

• A
  $A$ contractile protein capable of utilizing $ATP$ has been obtained from mitochondria.
• B
  Mitochondria have a highly folded inner wall.
• C
  Disruption of mitochondria yields membrane fragments which are able to synthesize $ATP$.
• D
  Mitochondria in animal embryos have a tendency to concentrate in cells which are to become part of locomotory structures.